European patent EP 1 239 139 in the name of the applicant company discloses an actuator for an aircraft engine nacelle mobile structure, comprising a motor intended to be mounted on a fixed part of said nacelle, an endless screw able to be turned by this motor, a slide intended to be connected to said mobile structure and comprising a nut in mesh with said endless screw, and a ball joint allowing some angular offset between the axis of said endless screw and the direction of travel of said slide.
In this actuator of the prior art, the ball joint prevents the shaft of the motor and the endless screw being subjected to excessively high stress if the slide is misaligned in relation to the motor.